(1) All stars are made up of Hydrogen gas. Since the Sun is too heavy, its center is very hot - up to 15,000,000 degree Celsius. At such a high degree temperature hydrogen creates lots of energy by changing itself into the helium liquid. This process is similar to Hydrogen Bomb. In the Sun, 5 billion Kg Hydrogen changes every second - which means numerous hydrogen bombs blast in it every second.

(2) Sun is also made of gas only, there is nothing like solids or liquids in it. Its diameter is 1,400,000 Km. Sun has the 32' (32 minute or about half the degree) diameter in the sky. Sun's material weight is 1.9891 x 10³⁰. This is 330,000 times of Earth's material weight. The Sun also has its magnetic field which is extended 100s of 1000s of Kms. Never look at the Sun with any telescope. Look at its reflection fallen on paper or wall. Sun's normal temperature is 5600 degrees Celsius. But wherever its magnetic field is strong, there temperature may be even 4000 degree. It means whatever light emanates from that part, it may be 1/4th of the normal, that is why it looks darker. The Sun emanates lots of flames and they can go up to 70,000 Kms high.

(3) The Sun can hold 1,300,000 Earths in him.

Sun Causes Day and Night and Seasons
The Sun makes our day and night and seasons on our Earth.
There are two movements of Earth - one revolving around the Sun and two, revolving on it own axis. Both continue together.
When our Earth revolves around the Sun it makes the seasons. Which ever part is nearer to Sun, there is Summer and the opposite part is Winter. At two places its distance from the Sun is alike so in those times there is Spring and Fall.
When Earth revolves on its own axis, it creates day and night. Whichever part of the Earth is in front of the Sun, there is day and the other part is in dark so there is night